Saudi officials say more than 2.5 million Muslim pilgrims are taking part in the annual Hajj rites, which peak on Saturday.

Hajj is the oldest and most sacred ritual of Islam. The pilgrimage focuses on the holy city of Mecca, the birthplace of the Prophet Muhammad.

Saudi Crown Prince Nayef bin Abdel Aziz said a record 1.8 million foreign pilgrims had arrived the kingdom as of Friday. He said they represented 183 nationalities. The foreigners will join hundreds of thousands of Saudi Muslims who are taking part in the ritual.

Most pilgrims visit the holy mosques in Mecca and nearby Medina, where they prophet Mohammed was buried over 1,400 years ago. They also gather on Mount Arafat, where the prophet is said to have delivered his last sermon.

The Hajj will end on Sunday with Eid al-Adha, or the Feast of Sacrifice.

The Hajj is one of the five pillars of Islam — one which every Muslim most fulfill, if possible, during his or her lifetime.